Objective: The aim was to investigate the time course of lower limb disease activity and walking disability in children with JIA over a 5-year course.
Methods: The Childhood Arthritis Prospective Study is a longitudinal study of children with a new JIA diagnosis. Childhood Arthritis Prospective Study data include demographics and core outcome variables at baseline, 6 months and yearly thereafter. Prevalence and transition rates from baseline to 5 years were obtained for active and limited joint counts at the hip, knee, ankle and foot joints; and walking disability, measured using the Childhood Health Assessment Questionnaire walking subscale. Missing data were accounted for using multiple imputation.
Results: A total of 1041 children (64% female), with a median age of 7.7 years at first visit, were included. Baseline knee and ankle synovitis prevalence was 71 and 34%, respectively, decreasing to 8-20 and 6-12%, respectively, after 1 year. Baseline hip and foot synovitis prevalence was <11%, decreasing to <5% after 6 months. At least mild walking disability was present in 52% at baseline, stabilizing at 25-30% after 1 year.
Conclusion: Lower limb synovitis and walking disability are relatively common around the time of initial presentation in children and young people with JIA. Mild to moderate walking disability persisted in ∼25% of patients for the duration of the study, despite a significant reduction in the frequency of lower limb synovitis. This suggests that there is an unmet need for non-medical strategies designed to prevent and/or resolve persistent walking disability in JIA.
Keywords: ankle; epidemiology; foot; hip; juvenile idiopathic arthritis; knee; lower limb; prevalence; synovitis; walking disability.